1. Field of the Invention
The present invention relates to a device for optically detecting an acidic substance or a basic substance, in particular, to detect fluid which exhibits acidity or basicity.
More particularly, the present invention relates to an abnormality detecting device for detecting, for instance, a degree of deterioration or an abnormal state in an electric apparatus in which the above-mentioned optically detecting device is used.
2. Discussion of Background
Heretofore, a so-called gas filled insulation apparatus wherein SF.sub.6 gas or the like having excellent insulating, quenching performance is used as an insulating medium, has been used as a transformer, an interrupter, and for a bus bar or the like.
If an abnormal state takes place in such electric apparatus, and when arcing or corona discharges occur or a short circuit takes place in an electric contact portion due to a fault in contact, such abnormality can not be easily detected from outside because electric components are covered by a metallic casing. Accordingly, when abnormality takes place, it is necessary to take the following steps for the restoration of the electric apparatus: the operation of the electric apparatus is stopped; an insulating medium such as SF.sub.6 is recovered; electric assemblies are dismantled; a fault component is detected, the fault component is repaired or replaced, and the electric apparatus is again assembled.
However, the dismantlement of the electric apparatus to inspect and find a fault component requires a large amount of work, there is difficulty in recovering the insulating medium, and it requires much time.
Therefore, a gas abnormality detecting device as in Japanese Unexamined Patent Publication No. 24844/1982 is proposed, for instance. However, the proposed device had a problem that it was difficult to obtain accurately information of abnormality.
There has been a strong demand of providing an optically detecting device capable of detecting a chemical change in fluid such as gas or liquid, especially detecting an acidic substance or a basic substance in the fluid with good sensitivity, for the above-mentioned abnormality detecting apparatus.